AMDGPU: Add new subtarget features for gfx9 flat instructions

[arsenm]

Summary

Flat instructions gain an immediate offset, and 2 new
sets of segment specific flat instructions are added.

[kzhuravl]

LGTM.

[arsenm]

r302729

lib/Target/AMDGPU/AMDGPU.td

 >;
 
 def FeatureFlatAddressSpace : SubtargetFeature<"flat-address-space",
   "FlatAddressSpace",
   "true",
   "Support flat address space"
 >;
 
+def FeatureFlatInstOffsets : SubtargetFeature<"flat-inst-offsets",
+  "FlatInstOffsets",
+  "true",
+  "Flat instructions have immediate offset addressing mode"
+>;
+
+def FeatureFlatGlobalInsts : SubtargetFeature<"flat-global-insts",
+  "FlatGlobalInsts",
+  "true",
+  "Have global_* flat memory instructions"
+>;
+
+def FeatureFlatScratchInsts : SubtargetFeature<"flat-scratch-insts",
+  "FlatScratchInsts",
+  "true",
+  "Have scratch_* flat memory instructions"
+>;
+
 def FeatureUnalignedBufferAccess : SubtargetFeature<"unaligned-buffer-access",
   "UnalignedBufferAccess",
   "true",
   "Support unaligned global loads and stores"
 >;
 
 def FeatureTrapHandler: SubtargetFeature<"trap-handler",
   "TrapHandler",

 >;
 
 def FeatureGFX9 : SubtargetFeatureGeneration<"GFX9",
   [FeatureFP64, FeatureLocalMemorySize65536,
    FeatureWavefrontSize64, FeatureFlatAddressSpace, FeatureGCN,
    FeatureGCN3Encoding, FeatureCIInsts, Feature16BitInsts,
    FeatureSMemRealTime, FeatureScalarStores, FeatureInv2PiInlineImm,
    FeatureApertureRegs, FeatureGFX9Insts, FeatureVOP3P, FeatureVGPRIndexMode,
-   FeatureFastFMAF32, FeatureDPP
+   FeatureFastFMAF32, FeatureDPP,
+   FeatureFlatInstOffsets, FeatureFlatGlobalInsts, FeatureFlatScratchInsts
   ]
 >;
 
 class SubtargetFeatureISAVersion <int Major, int Minor, int Stepping,
                                   list<SubtargetFeature> Implies>
                                  : SubtargetFeature <
   "isaver"#Major#"."#Minor#"."#Stepping,
   "IsaVersion",

lib/Target/AMDGPU/AMDGPUSubtarget.h

protected:
   bool HasVOP3PInsts;
   bool HasMovrel;
   bool HasVGPRIndexMode;
   bool HasScalarStores;
   bool HasInv2PiInlineImm;
   bool HasSDWA;
   bool HasDPP;
   bool FlatAddressSpace;
+  bool FlatInstOffsets;
+  bool FlatGlobalInsts;
+  bool FlatScratchInsts;
   bool R600ALUInst;
   bool CaymanISA;
   bool CFALUBug;
   bool HasVertexCache;
   short TexVTXClauseSize;
   bool ScalarizeGlobal;
 
   // Dummy feature to use for assembler in tablegen.
public:
   bool isXNACKEnabled() const {
     return EnableXNACK;
   }
 
   bool hasFlatAddressSpace() const {
     return FlatAddressSpace;
   }
 
+  bool hasFlatInstOffsets() const {
+    return FlatInstOffsets;
+  }
+
+  bool hasFlatGlobalInsts() const {
+    return FlatGlobalInsts;
+  }
+
+  bool hasFlatScratchInsts() const {
+    return FlatScratchInsts;
+  }
+
   bool isMesaKernel(const MachineFunction &MF) const {
     return isMesa3DOS() && !AMDGPU::isShader(MF.getFunction()->getCallingConv());
   }
 
   // Covers VS/PS/CS graphics shaders
   bool isMesaGfxShader(const MachineFunction &MF) const {
     return isMesa3DOS() && AMDGPU::isShader(MF.getFunction()->getCallingConv());
   }

lib/Target/AMDGPU/AMDGPUSubtarget.cpp

: AMDGPUGenSubtargetInfo(TT, GPU, FS),
     HasVOP3PInsts(false),
     HasMovrel(false),
     HasVGPRIndexMode(false),
     HasScalarStores(false),
     HasInv2PiInlineImm(false),
     HasSDWA(false),
     HasDPP(false),
     FlatAddressSpace(false),
+    FlatInstOffsets(false),
+    FlatGlobalInsts(false),
+    FlatScratchInsts(false),
 
     R600ALUInst(false),
     CaymanISA(false),
     CFALUBug(false),
     HasVertexCache(false),
     TexVTXClauseSize(0),
     ScalarizeGlobal(false),